This invention relates to a relatively high speed projector and rotary xerographic processor which produces dry, permanent, positive copies on continuous feed paper at a rate of at least 52 feet per minute.
Xerographic reproduction apparatus has been generally regarded as a necessity to many commercial enterprises since at least the early 1960's. The ability to produce permanent, positive copies on paper at a relatively high speed rate is particularly essential for obtaining and accessing stored microfilm records such as medical records, litigation pleading, technical literature and the like.
Johanson in U.S. Pat. No. 3049968 discloses a microfilm projection apparatus which was considered by many to be state-of-the-art in 1962, the date of issuance of his patent. The Johanson apparatus related particularly to an improved apparatus to project microfilm images at variable magnification ratios onto an electrostatically charged service of a xerographic plate which is moving normal to an exposure slit at constant rate. More specifically, the disclosure related to reproduction apparatus for use and conjunction with continuously xerographic printing apparatus for effecting xerographic reproductions at variable magnification ratios from continuously moving microfilm images onto a support service.
At one example of the process of xerography is disclosed in Carlson's Pat. No. 2297691. Reproduction of microfilm images onto a stationary receiving surface has conventionally been achieved by employing known projection techniques and the principals of silver-halide photography which may include means to effect magnification between the original and the image projected. Magnified projection of microfilm is usually attained using a single lens of appropriate fixed focal length mounted with its focal access in an optical path between the filmed image and receiving surface.
To effect projection at variable magnification ratios, means are provided to vary the length of the optical path and the lens position. To effect a wide range of magnification ratios by these means usually subjects the lens and optical path to a wide range of movement and renders the structure required therefore, impractical.
As an alternative, lenses of different focal lengths are manually interchanged to reduce the required range of movement. However, as stated in the Johanson patent, apparatus of this type is usually not suitable to automatic machines requiring compactness and rapid conversion over the full range of magnification ratios. In addition, when employing principals of silver-hallied photography the photo sensitive receiving service must be processed in accordance with methods well known in the photographic art which for expedient quantity reproduction is usually excessively time consuming and, therefore, considered objectionable for many applications. Because of these reproduction limitations encountered employing conventional apparatus for reproducing from microfilm, the use of microfilm as as a medium for recorded storing of printed matter is appreciably limited.
To effect quantity and continuous reproduction of images from moving microfilm, the surface receiving the projected image must also be continuously moving at a synchronized rate. Where it is intended to effect magnified projection the relative movement rates for each selected magnification ratio must be separately synchronized, that is, in a non-magnified projection from continuously moving microfilm, every lineal inch of image projected exposes a lineal inch on a receiving surface moving at the same rate; whereas, in an enlarged magnified projection of a 2 to 1 ratio, the length of film from which the image is projected consumes one half the moved length of the receiving surface, or in this instance, two inches of the receiving surface is exposed per inch of film projected. Therefore, an apparatus to effect projection over a wide range of magnification ratios onto a receiving surface moving at a constant rate requires cooperating apparatus enabling an inversely corresponding range of microfilm transport speeds.
Howard in U.S. Pat. No. 3732006 discloses a continuous microfilm or timing circuit which includes an SCR gate effective when turned on and off for respectively energizing and deenergizing shutter and clutch coils of the microfilmer.
Smitzer et al. in U.S. Pat. No. 3442585 discloses continuous rotary electrostaticgraphic apparatus for making micro images wherein a photo-conductive surface is moved in the direction of its lane through successive stations of charging, exposing and developing and simultaneously therewith a development electrode at the development station is reciprocated in a direction transverse to the direction of movement of the photo-conductive surface. Thus, the Smitzer disclosure provides a method and apparatus wherein micro images may be reproduced electrostatigraphically continuously so that the micro images may be recorded on a continuous strip of film.
Other know electrostatic copying apparatuses as well as related systems and equipment therefore are disclosed in the following U.S. Patents: U.S. Pat. Nos. 3,732,006; 3,442,585; 2,928,327; 2,829,025; 4,511,245; 4,227,803; 4,014,112; 4,685,798; 4,602,864; 4,530,596; 4,557,588; 4,090,787.
While generally satisfying the need of intermittent users such as law firms, physicians, offices and libraries and the like, those skilled in the art have recognized a particularly and improved projector and rotary xerographic processor which will provide a relatively high speed of reproduction, continuously, which produces dry, permanent, positive copies on plain paper rolls. Moreover, those skilled in the art have recognized a need for an apparatus which is conveniently operated by semi-skilled workers and which minimizes the occurrence of blurred images for producing "rippled effect" in the hard copy of documents reproduced. The present invention fulfills these needs.